A wide range of implantable medical devices (IMDS) are available for surgical implantation into humans or animals. Some common examples of such IMDs include the cardiac pacemaker, the implantable cardioverter defibrillator (ICD), and the implantable drug pump. Other examples include devices for stimulating or sensing portions of the brain, spinal cord, muscles, bones, nerves, glands, or other body organs/tissues.
Many of such IMDs incorporate sophisticated diagnostic capabilities to monitor an integrity of the IMD and/or patient conditions. For a variety of reasons, it may be appropriate to alert the patient when conditions require an immediate response from the patient, such as seeking medical attention, adjusting a medication dosage, etc. While many types of such alerts have been used in prior art IMDs, the most commonly implemented alert is an audible alert.
Unfortunately, such audible alerts have proven problematic in clinical practice due to false positives. For example, a patient may think that they heard the audible alert when, in fact, they heard a similar environmental sound, such as a cash register, smoke detector, etc. Such false positives are further exacerbated by environmental noise, impaired hearing capacity by the patient, etc. Similarly, false negatives may also be problematic in situations where the patient does not hear the alert, etc.
To address these issues, various prior art IMDs have incorporated a vibratory alert. Such vibratory alerts do not depend on a patient's auditory acuity, nor are they likely to be mistaken for something else. One concern with such vibratory alerts, however, involves the potential affect they may have on vibration-sensitive sensors (e.g. accelerometers, etc.). Specifically, a potential exists for a vibration of the vibratory alert to trigger a response by the vibration-sensitive sensor, thereby resulting in an undesired IMD rate response, etc.
For example, it is possible that a vibratory alert, when activated to generate sufficient vibration to make detection by the patient likely, may generate a level of vibration sufficient to affect a vibration-sensitive sensor. Thus, the vibration-sensitive sensor may interpret such vibration as increased physical activity. Under such circumstances, an IMD rate response algorithm may respond by inappropriately increasing the associated pacing rate.
While this is unlikely to cause direct harm to the patient, it may result in some degree of patient discomfort. For instance, the patient may experience a sensation of palpitations, racing heart, etc. More importantly, such interaction between the vibratory alert and the vibrations-sensitive sensor is contrary to the goal of matching the pacing rate to physiologic demand.
There is thus a need for overcoming these and/or other problems associated with the prior art.